1. Field of the Invention
The present invention relates to an information processing apparatus used for connection to an output device to print, display, or output particularly digital image data in information processing for data transfer, an information processing method, and a storage medium storing a program.
2. Description of the Related Art
When image data is output (display, print, or data transmission), real-time properties to output image data (or divided image data of a predetermined size) at regular intervals and thus, it is necessary to arrange a buffer memory in an output unit (a spooler in a printer to transfer graphic data to a printing unit, a frame memory in a display, an input/output unit and the like). In recent years, output images are at a faster frame rate and in higher resolution in an image processing apparatus such as a printer and display (or other information processing apparatuses) that processes and outputs input image data. With output images at a faster frame rate or in higher resolution, the amount of data output per unit time increases, which also increases the capacity of the buffer memory.
To prevent an increasing size of the capacity of the buffer memory, the data transfer between chips may be made faster by using a connection/communication method having a data transfer rate close to the throughput of the output unit.
According to the method discussed in Japanese Patent Application Laid-Open No. 2008-112413, data transfer is performed between a data processing unit and an image memory access processing unit connected via peripheral component interconnect (PCI)-Express, which is a high-speed serial bus. According to Japanese Patent Application Laid-Open No. 2008-112413, instead of a read request to a memory from the data processing unit, data transfer is realized by sending a command to cause transfer of image data read by the image memory access unit from the memory for write processing.
According to the method discussed in Japanese Patent Application Laid-Open No. 11-188953, the size of data transfer is set so that data transfer can be performed by using isochronous transfer defined for IEEE1394, which is a high-speed serial bus.
However, according to the method discussed in Japanese Patent Application Laid-Open No. 2008-112413, it is necessary to consider a waiting time (latency) before the data processing unit actually starts to receive data after a data transfer request.
According to the method discussed in Japanese Patent Application Laid-Open No. 11-188953, there is no method of monitoring buffer conditions in the data output unit and it is necessary to secure a certain level of buffer amount. Moreover, the data transfer unit becomes relatively large in a transfer mode in which the transfer interval is relatively large so that it may be impossible to decrease the buffer size.